<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<div id="app">
    <!-- 将msg与input输入框绑定， 双向绑定
        后台修改msg的值，input框的值也会改变
        input框中改变内容，msg也会跟着改
    -->
    <input type="text" v-model="msg">
    <h2>{{msg}}</h2>
</div>
<script src="../js/vue.js"></script>
<script>

    const app = new Vue({
        el: "#app",
        data: {
            msg: "hello"
        },
    })
</script>

</body>
</html>